1. Field of Invention
The present invention relates to the field of transducers used for the conversion of electrical variations into magnetic variations for the purpose of storage on magnetic media, for reconverting magnetic variations so stored into electrical variations, or for erasing such stored magnetic variations. More particularly, the present invention realtes to read/write heads for digital saturation recording, such as performed in rotating disc digital magnetic storage devices.
2. Description of the Prior Art
The type of magnetic recording head described herein is primarily used in rotating disc magnetic storage devices (hereinafter referred to as "disc files"). These storage devices are used primarily to provide digital storage capacity offering fast access to large amounts of stored information. In general, at the present state of the art, these disc files employ flying heads that may utilize self-actuating air bearings. The heads may be employed in a head-per-track arrangement or in a moving arm arrangement wherein the heads are moved generally along a radius of the disc so that a single head is associated with more than one track. The head-per-track arrangement facilitates rapid access to data since the heads do not have to move from track to track as they do in the moving arm disc file arrangements. The head-per-track arrangement does require a larger number of heads arranged in a relatively dense assembly and it is in such arrangement that the present invention has its greatest application.
The heart of a disc file is the magnetic head itself consisting of a magnetic core having a gap disposed near the media with windings to facilitate conversion of electric currents into magnetic fields. Basically a magnetic core consists of a torroid of magnetic material (generally ferrite in the present case) having a non-magnetic gap formed therein to provide directed magnetic fields that will impinge upon the magnetic recording medium (i.e., disc). This magnetic core takes many different physical forms, in practice primarily to facilitate ease of assembly in the process of manufacturing the complete head assembly. In the case at hand, the gapped torroid configuration is assembled from a gapped U-shaped core ("U-core") and a separate back bar to complete the magnetic circuit (See FIG. 1). This is a very common structure in disc file heads wherein the U-core is first placed into an air bearing slider assembly and later the windings and back bar are attached. This type of structure has the distinct advantage of permitting the coil to be inserted after the formation of the U-core.
As capacity and storage density are increased in the head-per-track disc files, the requirement for closer and closer track spacing becomes evident. As the cores are brought closer together crosstalk between cores becomes a limiting problem. The subject of this invention is a unique structure for reducing crosstalk between cores of the U-core/back bar type.
In previous heads of this head-per-track class, there are several primary sources of coupling between cores as follows (See FIG. 1): (1) Gap-to-gap coupling -- in this case fringing fields from one read/write (R/W) gap couples directly into the adjacent R/W gaps; (2) Coil-to-coil coupling -- some of the field generated by the write current flowing in the coil fails to couple into the core of the magnetic transducer. This stray field can couple into the adjacent cores or coils to cause write crosstalk; (3) Back gap-to-back gap coupling in this case a second piece of magnetic material is placed in physical contact with the U-core. Even though all surfaces are as flat as possible and polished to a very smooth finish, there will exist some air gap at the interfaces between the U-core legs and the back bar. These so-called back gaps provide a fringing field for crosscoupling between cores.